Rigging equipment is an essential part of most stages from the middle school level up to major performing arts centers. Rigging allows equipment on the stage to be raised, lowered, rotated and moved from side to side, serving the following functions:
Access to Equipment. The ability to raise and lower the stage lighting and other on stage equipment for adjustment, replacement of lamps and gels, and for maintenance is essential. Lighting equipment is frequently moved to meet the requirements of individual productions. All of these functions are most easily performed when the battens are brought to the floor level, rather than working off of ladders.
Masking of Equipment. Curtains are used to mask equipment from audience view. In many cases the height of the masking curtains will need to change to meet the requirements of specific productions. The ability to raise and lower the curtains easily is important.
Dramatic Effect. For many theatres, the primary use of the rigging equipment is to move scenery for dramatic effect. Not only does a well designed rigging system allow for simple, easy scene changes, many shows require that scenery move in front of the audience. This adds drama, and can be a key part of any production.
Counterweight rigging systems are the traditional method of raising and lowering stage equipment and consist of one or more rigging sets. A simple, manual counterweight set consists of a balanced system of weights and pulleys by which loads such as scenery, curtains, or lighting equipment can be raised and lowered. Each set is comprised of a load batten suspended from lift lines that pass over loft block sheaves, then over a head block at one side of the stage, and finally down to a counterweight arbor. The arbor holds weights that are adjusted by the user to balance (or counterweight) the load. Movement of the set is controlled by a rope hand line that passes from the top of the arbor, over the head block, down through a rope lock mounted on the locking rail, around a tensioning floor block and back to the bottom of the arbor.
While manually operated counterweight systems are economical to purchase and install, motorized rigging equipment is becoming more popular in new installations at all levels, from high schools to opera houses. The motorized rigging sets used on stage are generally “dead haul” sets, where the motor lifts the entire weight of the equipment without the use of counterweights. This eliminates the need for keeping sets balanced and addresses the safety concerns that come with improperly-balanced counterweight sets. The sets are operated using control systems ranging from simple pushbutton panels to sophisticated computer systems with the ability to record and play back cues.
Motorized rigging sets generally are easier to install and use than counterweight sets. Motorized winches are available in a wide range of speeds, capacities, types, and costs. Winches can be designed and built to meet a particular venue's specific requirements. Fixed speed winches are generally used for heavy loads which do not have to move dynamically in front of an audience. Examples include lighting battens, speaker clusters, and orchestra shell ceilings. The tremendous speed range possible with variable speed winches makes them ideal for use with scenery that must move in front of the audience. A winch that performs a subtle move at rate of less than a foot per minute can suddenly travel at several hundred feet per minute in the next cue.
The most widely used motorized winch has a single drum long enough to accommodate all of the lift lines required for the set. The drum is helically grooved so that the lift lines wrap neatly in a single layer, to avoid damage to the lift lines (which generally consist of wire rope) and to keep all lines lifting evenly. Winches can be located on the grid, galleries, or in a separate motor room. Head and loft blocks may be used to route the lift lines to the batten.
Traveling drum winches are built so that the drum translates or moves axially as it turns, keeping the point where the wire rope leaves the drum constant. Also known as zero fleet angle winches, these work well when there is very little distance between the drum and the head block. Typically, such winches include an acme screw or a ball screw that turns with the winch drum and engages a nut to cause the drum to translate axially.
It is known to provide modular assemblies that include a winch and a head block. Such assemblies, however, usually are mounted directly to structural support members (e.g., load bearing beams) in a theater or other venue in which rigging systems are used, and cannot be moved easily or adjusted. If the structural members of the theater are not located in locations suitable for mounting the winch and head block, it is necessary to move the structural support members or to offset the mounting of the winch and head block. Either of these options is an expensive and complicated process.
Typical winch assemblies use winch drums that have a standard length or that are custom manufactured to fit a specific application. Standard length winch drums may not be the ideal size for certain applications, while custom manufactured drums may be too expensive.
Typical rigging systems in which the winch and head block form a modular assembly require the entire winch portion to translate axially as lines wind and unwind on the drum. Where the rigging system is installed vertically, this requires the entire winch assembly to work against gravity in one direction of travel. Because the motor and gearbox are the heaviest components of the winch assembly, this imposes demands on the axial drive mechanism that would be unnecessary if the drum portion of the winch assembly could translate separately.
When a conventional rigging system is installed horizontally (the predominant installation), the drum generally must be supported by a bearing that is separate from the nut that engages the translating screw. When the nut also functions as a bearing to support the drum, the vertical forces exerted on the translating screw cause binding of the thread engagement between the translating screw and the nut.
Finally, some winch and head block assemblies known in the art use overly complicated or unreliable brake assemblies. Because such assemblies often support the entire dead weight of theater loads, including curtains, set backdrops, lights and/or other items, it is important that they incorporate reliable brake mechanisms to prevent unintentional and uncontrolled descent of a load. In one assembly known in the art, the brake mechanism includes a solenoid that activates a pawl when an uncontrolled condition is electronically sensed. Such a system does not account for failure of the electronic sensing system and would therefore be an inadequate brake if the electronic sensing system were to fail.
What is needed is a theater rigging system that can easily be attached to structural members of a theater or other venue in which theater rigging is required.
What is further needed is a theater rigging system that incorporates an easily adjustable winch assembly and head block.
What is further needed is a theater rigging system that incorporates an easily customizable winch drum, allows the winch drum to translate independent of the motor and gearbox.
What is also needed is a theater rigging system that incorporates a winch a with a simple, but reliable brake to prevent unintentional and uncontrolled descent of a theater load.
It is therefore an object and advantage of the present invention to provide a theater rigging system that can easily be attached to structural support members of a theater or other venue in which theater rigging is required.
It is a further objective and advantage of the present invention to provide a theater rigging system that includes a winch assembly and head block that can easily be positioned at a variety of positions with respect to the structural support members of a theater or other venue in which theater rigging is required, and once positioned, can easily be fixed in place, and additionally can easily be sized to fit a wide variety of applications.
It is a further objective and advantage of the present invention to provide a winch drum that can be customized for a variety of applications and that translates axially independent of the winch motor and axle.
It is yet a further objective and advantage of the present invention to provide a theater rigging system that includes a winch assembly and head block with a simple but reliable brake that prevents unintentional and uncontrolled descent of theater loads.